The plots of the estimated Rt over the most recent weeks show the Rt following a declining trend from peaks of around 1.50 to a plateau just below 1. This downward trend in Rt from the peak is still largely driven by the indices of mobility, and particularly by the recent school holiday.
The incidence of deaths has been gradually increasing since mid June, although the actual numbers remain low in comparison to the peaks of the first two waves of infection. In line with our previous publication, our projections for the number of deaths suggest that we are now at, or close to, the peak of the current summer wave.
Plots of the IFR over time show that from the end of January we estimate a decreasing IFR in all adult age groups, but most steeply in the older ages. This drop indicates the benefits of immunisation against death over and above the benefits against infection. Specifically, there is an estimated fall to a still-high 2.5% (2.4%–2.7%) in the over-75s and 0.12% (0.12%–0.13%) overall in mid-July. The overall impact of the immunisation programme can be seen more clearly in the ‘All Ages’ plot, where the precipitous decline in IFR since late January is a product of this efficacy against death but also of the increasing proportion of infections in young people; older age groups are immunised and become more protected against infection. There is an initial suggestion that the IFR may have risen slightly over the last month, and this is to be monitored.
For context, alongside the data used here, reported new positive tests have shown a very gradual increasing trend over the last couple of weeks. This trend is highly dependent on the targeting of testing and the public’s testing behaviour and, therefore, is difficult to interpret. However, a downturn in hospital admissions has plateaued, subject to some regional variation. Prevalence of infection, as estimated by the ONS Coronavirus Infections Survey, remains high, staying constant at around 1.30% in England, having declined from around 1.5% in mid-to-late July.
Real-time tracking of an epidemic, as data accumulate over time, is an essential component of a public health response to a new outbreak. A team of statistical modellers at the MRC Biostatistics Unit (BSU), University of Cambridge, are working to provide regular now-casts and forecasts of COVID-19 infections and deaths. This information feeds directly to the SAGE sub-group, Scientific Pandemic Influenza sub-group on Modelling (SPI-M), and to regional Public Health England (PHE) teams.
We fit a transmission model (Birrell et al. 2020) to a number of data sources (see ‘Data Sources’), to reconstruct the number of new COVID-19 infections over time in different age groups and NHS regions, estimate a measure of ongoing transmission and predict the number of new COVID-19 deaths.
We use:
Data are stratified into eight age groups: <1, 1-4, 5-14, 15-24, 25-44, 45-64, 65-74, 75+, and the NHS England regions (North East and Yorkshire, North West, Midlands, East of England, London, South East, South West).
Value of \(R_t\), the average number of secondary infections due to a typical infection today.
The percentage of a given group that has been infected.
NB: negative growth rates are rates of decline. Values are daily changes.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | -0.02 | -0.02 | -0.01 |
| East of England | 0.00 | -0.02 | 0.02 |
| East Midlands | -0.02 | -0.05 | 0.00 |
| London | -0.01 | -0.03 | 0.01 |
| North East | -0.05 | -0.08 | -0.03 |
| North West | -0.03 | -0.05 | 0.00 |
| South East | -0.02 | -0.04 | 0.00 |
| South West | -0.02 | -0.04 | 0.01 |
| West Midlands | -0.04 | -0.07 | -0.02 |
| Yorkshire and The Humber | -0.02 | -0.04 | 0.00 |
Halving times in days, if a region shows growth than value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 45.09 | 28.94 | 116.32 |
| East of England | NA | 44.28 | NA |
| East Midlands | 27.94 | 14.52 | NA |
| London | 59.87 | 22.12 | NA |
| North East | 13.63 | 8.61 | 25.39 |
| North West | 24.40 | 12.68 | 189.92 |
| South East | 34.52 | 17.34 | 2465.60 |
| South West | 38.41 | 16.87 | NA |
| West Midlands | 15.56 | 9.50 | 32.60 |
| Yorkshire and The Humber | 37.73 | 18.36 | NA |
Doubling times in days, if a region shows decline then the value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | NA | NA | NA |
| East of England | 206.76 | 30.54 | NA |
| East Midlands | NA | 23559.11 | NA |
| London | NA | 125.76 | NA |
| North East | NA | NA | NA |
| North West | NA | NA | NA |
| South East | NA | NA | NA |
| South West | NA | 125.32 | NA |
| West Midlands | NA | NA | NA |
| Yorkshire and The Humber | NA | 3409.42 | NA |
NB: negative growth rates are rates of decline. Values are daily changes.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 0.00 | -0.01 | 0.01 |
| East of England | 0.02 | 0.00 | 0.04 |
| East Midlands | 0.00 | -0.02 | 0.01 |
| London | 0.00 | -0.01 | 0.02 |
| North East | -0.02 | -0.03 | -0.01 |
| North West | -0.01 | -0.02 | 0.01 |
| South East | 0.00 | -0.01 | 0.02 |
| South West | 0.00 | -0.01 | 0.02 |
| West Midlands | -0.02 | -0.03 | 0.00 |
| Yorkshire and The Humber | 0.00 | -0.01 | 0.02 |
Halving times in days, if a region shows growth than value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 1308.73 | 104.23 | NA |
| East of England | NA | NA | NA |
| East Midlands | 178.64 | 37.98 | NA |
| London | NA | 72.91 | NA |
| North East | 32.34 | 20.08 | 114.31 |
| North West | 70.15 | 27.90 | NA |
| South East | NA | 56.81 | NA |
| South West | NA | 46.65 | NA |
| West Midlands | 39.56 | 22.76 | 201.31 |
| Yorkshire and The Humber | NA | 73.96 | NA |
Doubling times in days, if a region shows decline then the value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | NA | 120.31 | NA |
| East of England | 40.35 | 19.72 | 433.45 |
| East Midlands | NA | 56.14 | NA |
| London | 194.49 | 40.72 | NA |
| North East | NA | NA | NA |
| North West | NA | 91.63 | NA |
| South East | 589.66 | 43.50 | NA |
| South West | 737.03 | 37.21 | NA |
| West Midlands | NA | NA | NA |
| Yorkshire and The Humber | 185.23 | 38.09 | NA |
The shaded areas show periods of national lockdown, the green lines the dates (once confirmed) of the steps in the roadmap in the UK Governement’s COVID-19 Response – Spring 2021, and the red line shows the date these results were produced (17 Aug).